MEASLES

Measles is a highly contagious viral infection which is spread by air-droplets {through coughing and sneezing} and causes  syndromes of intoxication, catarrhal inflammation of respiratory tracts, conjunctiva and rashes on the skin. Measles virus is single-stranded, negative-sense, enveloped, non-segmented RNA virus of the genus Morbillivirus within the family Paramyxoviridae. 

Risk factors include immunodeficient patients, imnnuosuppression in patients after organ transplant who are on immnuosuppressant drugs such as corticosteroids, or people that travel to areas where measles commonly occurs or contact with travelers from such an area.

Pathophysiology

Upon entry into the mucosa,the measles virus infects the epithelial cells of the trachea and bronchi, and it binds to the target receptor on the hosts cells using a protein on its surface called Hemagglutinin {H protein}. Once bound,the fusion or the protein helps the virus fuse with the membrane and ultimately get inside the cell. The single-stranded negative-sense RNA properties of the virus means it firstly has to be transcribed by RNA polymerase into positive-sense mRNA strand after which it will be ready to be transcribed into viral proteins, wrapped in the cell’s lipid envelope and sent out of the cell as a newly made virus. Within days,the virus spreads through local tissue and is picked by the dendritc cells and alveolar macrophages,carried from the local tissue to the local lymph node,and from there it continues to spread, eventually getting into blood and spreading to more lung tissue and other organs like intestines and brain.

 

“4 D’s {four days of fever}

“3 C’s {cough coryza and conjunctivitis}

Clinical presentation

Incubation period typically lasts between 10-14 days after exposure.

Prodromal period follows,lasting for about four days {4 D’s of fever can be as high as 40^0c},and presents with the classic 3 C’s {cough, corryza, conjunctivitis}. Koplik’s spots are also seen inside the mouth and are diagnostic for measles, but are temporary and therefore rarely seen. Koplik spots are small white spots that are commonly seen on the inside of the cheeks opposite the molars. They usually disappear by the second day of the exanthema. Temp is usually high of the first day,but reduces as days go by,which later increases as exanthema period begins.

Exanthema period : Second increase of temperature. Initial lesions are noted on the forehead and face. During 3-4 days they spread downward, involve the trunk and extremities. The rashes consist of an erythematosus maculo papular eruption. They are initially discrete but then became confluent on the areas of initial involvement. And finally as the rash resolves,a pigmentation occurs.

Complications

Complications of measles are common and can mild such as diarrhea,or severe as in viral pneumonia, bronchitis and encephalitis. It is well known that measles causes immune suppression which leads to development of secondary bacterial pneumonia, bronchitis or otitis media. 

People who are at high risk for complications are infants and children aged less than 5 years; adults aged over 20 years; pregnant women; people with compromised immune systems, such as from leukemia, HIV infection or innate immunodeficiency; and those who are malnourished or have vitamin A deficiency. Complications are usually more severe in adults who catch the virus.

 

Diagnosis

A clinical diagnosis usually must have 

  • history of at least three to four days of fever with one of either
  • cough
  • conjunctivitis
  • coryza

Confirmation can be made by lab work up findings of either

  • positive measles IgM antibodies
  • isolation of measles virus RNA from respiratory specimens {but note that viral isolation is technically difficult}
  • salivary measles-specific IgA testing {in patients whose blood cant be drawn}
  • Cytoscopic examination of smears from the pharynx – presence of typical multinuclear giant cells

 

Differential diagnose should be performed between scarlet fever, Epstein-Barr viral infection, meningococcal sepsis, pseudotuberculosis, Kawasaki syndrome, Stevens-Johnson syndrome, adenovirus, enterovirus infection, diaper rashes, Rheumathoid arthritis systemic form, and allergic rashes.

During prodromal period – between other upper respiratory tract viral infections. 

 

Treatment 

There is no specific antiviral treatment if measles develops. Instead the medications are generally aimed at treating superinfections, maintaining good hydration with adequate fluids, and pain relief.

  1. Bed rest up to body temperature drops to normal levels.
  2. Adequate hydration with oral fluids.
  3. Vitaminized milk {vegetable foods}
  4. Control of fever (when the temperature is more than 38.5-39˚C); in children before 2 mo and in case of perinatal CNS damage, seizures in the history, severe heart diseases – when the temperature is up to 38˚C with acetaminophen (paracetamol 10-15 mg/kg not often than every 4 hours (not more than 5 times per day) or ibuprophen 10 mg/kg per dose, not often than every 6 hours.
  5. Nasal drops (in infants before 6 mo – physiologic saline solutions as Salin; in elder children – naphtizin, rhinasolin, nasivin for children 1-2 drops 3 t.d. in the nostrils, not more than 3 days
  6. In case of dry cough – cough suppressors (such as dextramethorphan, synecod)
  7. Mucolytics in case of the moist nonproductive cough (ambroxol, acetylcystein etc.)
  8. Looking after oral cavity (gurgling with boiled water, antiseptic fluids).
  9. Looking after conjunctiva (washing with boiled water, concentrated tea, sulfacyl Na in drops)
  10. Vitamin A orally.

 

  • In case of bacterial complication – antibacterial therapy should be used.
  • In case of severe episodes – corticosteroids (1-2 mg/kg for 2-3 days).
  • In case of croup: mist tent with 25-30 % oxygen inhalation, antianxiety medicines, steroids and mechanical ventilation in severe cases.
  • In case of meningitis: steroids, dehydrates, parenteral detoxication (albumin, plasma), anticonvulsants.

 

Prevention

  1. Specifically active immunization by MMR vaccine (measles, mumps, rubella) at age 12 months. Revaccination at 4 to 6 years or at 10 to 11 years.
  2. Specifically passive prophylaxis with immune serum globulin in a dose of 0.25 ml/kg as a post exposure prophylaxis.
  3. Non specific: – isolation of ill person until 5th day of the exanthema period, isolation of contact person from 8 to 21 day after exposure.